Your car does not have a knock sensor. Cars with knock sensors and associated technology will indeed retard the timing when knock due to low grade fuel is sensed.

That said, yes such a car will indeed tolerate regular fuel without hurting the engine, but it will hurt fuel mileage. Now that gas prices are up, the difference between the price of regular and premium as a percentage is less. When regular was $1.10 a gallon, premium was $1.30 a gallon making premium about 18% more expensive. With regular now at $2.57 and premium at $2.77, premium is only about 7.7% more expensive.

In a high compression engine such as many late model MB's, running regular instead of premium would be false economy.

Back to your car. Since there is no knock sensor, you could do damage to your engine.

You should take comfort in the fact that your high compression engine is more fuel efficient than if it were the same engine, but with lower compression ratio allowing the use of regular fuel.

BTW, adjusted for inflation we still have cheaper fuel than in many years past. 1981 took a bigger percentage of our paychecks to buy fuel than it does today.

Have a great day,